Deserialization with binaryformatter

问题

I have a program that serializes an object and sends it over a network:

TcpClient client = new TcpClient();
client.ReceiveTimeout = 10000;
client.SendTimeout = 10000;
IPEndPoint serverEndPoint = new IPEndPoint(IPAddress.Parse("127.0.0.1"), 8888);
client.Connect(serverEndPoint);

BinaryFormatter binaryformatter = new BinaryFormatter();

NetworkStream networkStream = client.GetStream();
if (networkStream.CanWrite)
{
    binaryformatter.Serialize(networkStream, kort);
}

And on the other side I receive and deserialize the code as such:

TcpClient tcpClient = (TcpClient)client;
tcpClient.SendTimeout = 10000;
tcpClient.ReceiveTimeout = 10000;
NetworkStream clientStream = tcpClient.GetStream();
try
{
    if (clientStream.CanRead)
    {
        BinaryFormatter binaryformatter = new BinaryFormatter();
        binaryformatter.Binder = new AllowAllAssemblyVersionsDeserializationBinder();

        Kort tempkort = (Kort)binaryformatter.Deserialize(clientStream);
        SetImage(tempkort);
    }
}
catch (SerializationException e)
{
    MessageBox.Show("Failed to deserialize. Reason: " + e.Message);
    throw;
}
finally
{
    clientStream.Close();
    tcpClient.Close();
}

But when I deserialized I got this error about an assembly missing:

"An unhandled exception of type System.Runtime.Serialization.SerializationException occurred in Server.exe Additional information: Unable to find assembly 'Client, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null'.

which I solved with this:

sealed class AllowAllAssemblyVersionsDeserializationBinder : SerializationBinder
{
    public override Type BindToType(string assemblyName, string typeName)
    {     
        String currentAssembly = Assembly.GetExecutingAssembly().FullName;

        // In this case we are always using the current assembly
        typeName = "Server.Kort";
        assemblyName = currentAssembly;

        // Get the type using the typeName and assemblyName
        Type typeToDeserialize = Type.GetType(String.Format("{0}, {1}",
            typeName, assemblyName));

        return typeToDeserialize;
    }
}

But now that I try to do it, I keep getting an error that says:

"Object of type Server.Kort cannot be converted to type Server.Kort+kortvalör."

And I don't know how to fix it.

回答1:

The class Kort on the sending side must contain an instance of a nested type (perhaps an enum?) called kortvalör. And, since BinaryFormatter serializes public & private fields instead of properties, the nested type could be completely invisible to the outside world, but still get serialized.

For instance, I was able to reproduce your exception "Object of type Server.Kort cannot be converted to type Server.Kort+kortvalör" using your binder with the following class:

[Serializable]
public class Kort
{
    // Private enum that is invisible to the outside world.
    enum kortvalör 
    {
        Zero,
        One,
        Two,
        Three
    }

    kortvalör valör = kortvalör.Three;

    public int Value
    {
        get
        {
            return (int)valör;
        }
        set
        {
            // Check to make sure the incoming value is in a valid range.
            var newvalör = (kortvalör)value;
            if (Enum.IsDefined(typeof(kortvalör), newvalör))
                valör = newvalör;
            else
                valör = default(kortvalör);
        }
    }
}

When deserializing the class above, your binder will be called twice, once with the typeName for Kort -- and then once with the typename "MyClientNamespace.Kort+kortvalör". Since your binder ignores the incoming typeName and returns typeof(Kort), this fails.

You have a few options to solve this problem:

Extract your class Kort into a shared DLL and link it with both the sending and receiving applications. Then the problem goes away.
Create duplicates of all types referenced by Kort in both the sending and receiving applications -- including private nested types -- and remap the type names appropriately inside a smarter version of your SerializationBinder. The article Advanced Binary Serialization: Deserializing an Object Into a Different Type Than the One It was Serialized Into has an example of how to do it.
Consider using a different serialization format that serializes properties rather than private fields. BSON is one option. Protobuf-net is another.

来源：https://stackoverflow.com/questions/30196506/deserialization-with-binaryformatter

标签

serialization

.net-assembly

binaryformatter